The present invention relates to networks. More specifically, the invention relates to techniques for supporting electrical and optical connections in network devices.
The earliest networks used electrical signals over copper wires. Although networks have come a long way over the years, this is still a popular transmission methodology. However, light signals over optical cables is now the standard transmission methodology for high bandwidth network connections.
As fiber optics developed, many new technologies emerged to enhance their use. For example, fairly recently, a specification for a new generation of optical modular transceivers was developed named “small form-factor pluggable” (SFP). SFP transceivers are designed to be high bandwidth, small physical size and easily changeable (including being hot-swappable). The changeable nature or SFPs allows repairs and upgrades to be done much more efficiently.
Network devices typically have a backplane in which numerous line cards can be inserted. As SFPs are optical transceivers, they are typically found on line cards that support optical connections. Thus, there are line cards that support multiple electrical connections (e.g., RJ45) and other line cards that support multiple optical connections. Because the underlying format and encoding of the signals is different, line cards were typically designed as either electrical or optical.
However, there soon became a demand for line cards that could support both electrical and optical connections. This has been accomplished using what will be called “copper SFPs” because they plug into ports on line cards like optical SFPs. These implementations have numerous disadvantages.
First off, this approach typically utilizes a conversion integrated circuit (IC) within the optical SFPs in order to convert from optical to electrical formats and encoding that are supported by the line card. Additionally, an interfacing application specific IC (ASIC) may be required that incorporates a proprietary SGMII interface to support lower data rates such as 10BASE-T and 100BASE-T. The additional circuitry adds complexity and cost that has made this solution less than satisfactory.
It would be beneficial to have innovative techniques for allowing line cards to support optical and electrical connections, including the capability to allow a port to support optical and electrical transceivers. Additionally, it would be beneficial if none or a small amount of additional circuitry was needed to provide these capabilities.